Apparatus for purifying water

ABSTRACT

The invention relates to a method for purifying water by forming in an electrolytic cell molecular halogen, hypohalic acid, hypohalite ions or combinations thereof, from halide ions dissolved in the water; and dissolving one or more soluble metal salts in the water to provide corresponding metal ions. The invention also relates to a system for purifying water, having an electrolytic cell comprising a plurality of electrodes sufficient to electrolytically convert halide ion in the water into molecular halogen, hypohalic acid, or hypohalite ions, or combinations thereof; and a metal generator, which provides concentrations of one or more metals to the water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase of International ApplicationNo. PCT/US02/34491 filed on Oct. 28, 2002, which claims priority to U.S.Ser. No. 10/014,944 filed on Oct. 26, 2001, now U.S. Pat. No. 6,761,827,the entire contents of which are incorporated herein by this reference.

FIELD OF THE INVENTION

This invention relates to the methods and apparatus for purifying andsanitizing water using a combination of electrolytic purification andintroduction of microbicidal metal species into the water. Moreparticularly, the invention relates to the systems and methods forcombining electrolytic purification and the introduction of biocidalmetal ions into the water.

BACKGROUND OF THE INVENTION

Electrolytic purification of water has been carried out for some time.The process involves the purification of water that is saline, i.e.,that contains some concentration of halide ion. For instance, in manyswimming pools in Australia, where electrolytic purification of poolwater is currently more popular than in the United States, a slightsalinity level is achieved by dissolution of quantities of sodiumchloride into the pool water. The water, with its dissolved halide ion,is passed through an electrolytic cell. The halide ions are oxidized byelectrolysis to form hypohalic acid, hypohalite ions, or both (believedto occur through the intermediate of molecular halogen), which haveknown utility in disinfecting water (and whose use is typically known as“chlorinating” the water). In addition, he electrolysis reactionconverts water into hydrogen and oxygen; some of the oxygen is convertedfurther into ozone, which also has a disinfecting effect on the poolwater.

Electrolytic purification is desirable because it is safe, effective,and for applications such as swimming pools, hot tubs, spas, etc., iteliminates much of the need for the pool owner or operator to handlechemicals and monitor water chemistry. The salinity levels necessary toachieve effective chlorination levels are typically well below theorganoleptic thresholds in humans, and the primary chemical required tobe handled by the operator is a simple alkali metal halide salt. Inaddition, operation of the electrolytic cell is comparatively easy, andrequires little attention beyond ensuring the proper current and voltagelevels are set, and maintaining the correct salinity levels in thewater.

One of the disadvantages associated with electrolytic purification isthe cost of the electrolytic cell, as well as the cost of replacementelectrodes, which can corrode, become fouled with scale and the like orotherwise become inactivated over time. These costs are primarily drivenby the size of the electrodes, which are typically constructed fromtitanium coated with platinum or ruthenium. Electrodes having a surfacearea sufficient to generate adequate chlorine levels represent asignificant portion of the cost of installing and maintaining anelectrolytic purification system. In addition, electrolytic cell life islimited due to the current density through the cell over time.

The introduction of microbicidal metals into water to sanitize it hasalso been suggested for and used in various water purificationapplications, such as in pools and spas. In particular, various methodsof introducing metal ions, such as silver ions or copper ions, into thewater have been proposed. The use of these ions to purify, e.g., poolwater, results in decreased need for chlorination. Highly chlorinatedpool water is often uncomfortable to, and is thought to possibly haveadverse effects on the health of, swimmers and bathers, decrease theuseful life of swimwear, etc. One method of introducing such ions intowater that has been proposed involves the use of sacrificial electrodescontaining metals corresponding to the desired ions, including alloys ofsilver and copper, and electrolytically dissolving the metals into thewater. Other methods include contacting the water with substrates thathave been coated or impregnated with metal, soluble metal salts or somecombination thereof. These methods can be difficult for pool owners tocontrol, and as a result, can sometimes provide unreliable control ofmetal delivery, and can cause stained surfaces when too much metal hasbeen delivered, or result in insufficient sanitation when too littlemetal has been delivered.

SUMMARY OF THE INVENTION

This invention results from the surprising discovery that the use ofelectrolytic purification of water can advantageously be combined withthe introduction of microbicidal metals to provide a purification systemand method that is safe, effective, and economical. The combination ofmicrobicidal metals with electrolytic purification allows decreasedlevels of metal ion to be present, along with decreased chlorine levels.As a result, there is decreased likelihood of unpleasant or unhealthyside effects from either technique, such as staining of pool surfaces,chlorine damage to hair and clothing of swimmers and bathers, reducedopportunity to produce chloramines, etc. At the same time, the poolwater is sanitized for a wide variety of microorganisms by the use ofmultiple methods. Finally, the presence of metals in the water, at leastthrough the resulting decrease in necessary chlorine levels, can reducethe size of electrodes necessary to maintain appropriate levels ofprotection. This results in a substantial decrease in the cost ofdeploying and maintaining an electrolytic purification system.

In one embodiment, the invention relates to a method for purifying andsanitizing water by forming in an electrolytic cell molecular halogen,hypohalic acid, hypohalite ions, or combinations of these, from halideions dissolved in the water; and dissolving one or more metals in thewater.

In another embodiment, the invention relates to a system for purifyingand sanitizing water, having an electrolytic cell comprising a pluralityof electrodes sufficient to electrolytically convert halide ion in thewater into molecular halogen, hypohalic acid, hypohalite ions, orcombinations of these; and a metal generator, which providesconcentrations of one or more metals to the water.

According to certain embodiments of the invention, purification of abody or stream of water is accomplished via an apparatus that includes ahousing having an inlet and an outlet. Water is directed into the inlet,which is in fluid communication with a metal generating chamber,containing media that introduces metal concentrations into the water.The media may contain metallic material which dissolves or dispersesinto the water, or may contain soluble metal salts, or combinationsthereof. At least some of the water flows through or otherwise contactsat least a portion of the media, thereby acquiring some of the metallicmaterial, generally in the form of metal ions. The metal generatingchamber is also in fluid communication with an electrolytic purificationchamber, containing an electrode assembly cartridge, which includes atleast one electrolytic cell. At least a portion of the water directedinto the inlet and passing through the metal generating chamber alsoflows through the electrolytic purification chamber and contacts theelectrode assembly cartridge, which thereby electrolytically convertsthe halide ion in the water to chlorine. The water eventually exits thehousing via the housing outlet.

These and various other embodiments of the invention result in a methodand system that achieve the advantages of electrolytic purification andthe advantages of microbicidal metal ion purification, but vastly reducethe concomitant disadvantages of each. Further, the combination oftechniques results in a significantly more economical purificationprocess than is achievable with electrolytic purification alone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a water sanitization apparatus accordingto certain of the various embodiments of the invention.

FIG. 2 is a exploded perspective view of the components of the watersanitization apparatus according to FIG. 1.

FIG. 3 is a cross-sectional view of a water sanitization apparatusaccording to FIG. 1.

FIG. 4 is a perspective view of an electrode assembly according tocertain of the various embodiments of the invention.

FIG. 5 is a cross-sectional view of an electrode assembly according toFIG. 4.

FIG. 6 is a plan view of differently sized electrode platescorresponding to varying water treatment capacities according to certainof the various embodiments of the invention.

FIG. 7 is a side view of a water sanitization apparatus according toanother of the various embodiments of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The methods and apparatus described herein can be used to sanitize andprotect water from the growth of microorganisms, such as bacteria,virii, fungi, algae, and the like. This sanitizing and protecting effectcan be used for water in a variety of applications, including swimmingpools, hot tubs, spas, as well as wastewater treatment facilities,cooling towers, and the like. The description below will focus onapplications for swimming pools, hot tubs, spas, and the like. Thosefamiliar with the art of water purification will be able to modify theteachings below to other water treatment applications without theexercise of undue experimentation.

In many cases, the halide ion dissolved in the water will be chlorideion, with the result that the halogen gas formed is molecular chlorine,and the hypohalic acid formed by electrolysis will be hypochlorous acid,HOCI. It will be understood, however, that other halide ions and/oracids, such as bromide, iodide, hypobromous acid, or combinationsthereof, can be present in the water and oxidized by electrolysis toform similar acids and which can dissociate to the correspondingoxidized ions, which may also have a sanitizing effect.

Similarly, the metal introduced into the water will, in many cases,contain silver, copper, or some combination thereof, because of therecognized bactericidal, viricidal, and algaecidal properties of thesemetals. Other metals, such as zinc, can also be introduced into thewater, alone or combined with the metals described above, to provide,e.g., additional biocidal activity. The metals can be introduced asmetallic, zero valence material, or as metal ions that can be introducedinto the water by dissolution of soluble metal salts, or by thedissolution of the metal itself. For example, silver ion can beintroduced into the water through the dissolution of silver nitrate, orthrough the dissolution of metallic silver as the result of conversionto silver oxide and subsequent conversion of the oxide to more solublesilver species. Copper ion can be introduced into solution through thedissolution of copper sulfate or copper chloride, for example. Mixturesof different salts, or of salts with metallic material, may be combinedtogether to provide the necessary concentration of metal ions in thewater.

One particular material suitable for introducing metal ions into thewater is a combination of soluble copper salt and metallic silver,deposited on a substrate, and sold under the name Nature²® by ZodiacPool Care, Inc.

The electrodes used in the electrolytic cell may be of any suitablematerial. However, the electrodes are generally not sacrificialelectrodes made of copper, silver, zinc, or any metal species that it isdesired to dissolve in the water, or any alloy thereof. One suitableelectrode material is titanium, which may be coated to reduce corrosionand fouling, e.g. with a precious or semiprecious metal, such asplatinum, ruthenium, or iridium.

The surface area of electrodes used in the invention can be considerablyreduced as compared to the surface area of electrodes used in simpleelectrolytic purification (i.e., without the presence of microbicidalmetal ions). The amount of this reduction typically ranges from about25% to about 90% of the area of electrodes used in simple electrolyticpurification. Assuming a halide ion concentration ranging from about2500 ppm to about 5000 ppm, which is a typical range for salinated poolwater, and a DC voltage power supply of about 5 to about 25 V, electrodesurface areas generally varying between about 10 cm² to about 150 cm²,will produce a chlorine concentration (calculated as Cl₂) of betweenabout 0.5 ppm and about 2.0 ppm. This is sufficient to sanitize andprotect a typical swimming pool provided that the concentrations ofsilver and copper ions in the water are maintained between about 0.010ppm and about 0.080 ppm (silver ion) and between about 0.020 ppm andabout 0.100 ppm (copper ion), respectively. The bulk concentration ofsilver and copper ions is not necessarily required to be constantlymaintained, and is therefore substantially variable. While not wishingto be bound by any theory, it is believed that additional bactericidaland fungicidal effects are provided by ions that collect on surfaces incontact with the water, such as pool walls, filter walls, and on theinterior surfaces of the housing of the invention itself. These surfacesprovide large surface areas that are associated with microbicidal ionsfrom the purification system of the invention, and it is believed thatthese large surface areas provide a significant contribution to theoverall microbicidal effect of the invention. By contrast, in theabsence of silver or copper ion, the chlorine content of the water(calculated as Cl₂ will generally have to be maintained at between about2.0 ppm and about 6.0 ppm, requiring an electrode area of between about75 cm² and about 200 cm².

The electrode voltage in the electrolytic cell typically ranges betweenabout 5 V and about 25 V, and current flow across the electrode rangesfrom about 0.75 A to about 12.0 A. The source of microbicidal metal ionsis generally provided in amounts capable of introducing bactericidally,viricidally, fungicidally and/or algaecidally effective amounts of metalion into the water. Generally, these levels of metal ions range fromabout 0.010 ppm to about 0.500 ppm. When Nature²® is used as the sourceof metal ions, approximately 1.15 g to approximately 7.75 g of materialper 10,000 gal. of water can be used to provide effective concentrationsof silver and copper ion.

In general, sanitization of a body of water can be accomplished byremoving a flow stream from the water, passing this flow stream throughthe electrolytic cell, and returning the treated flow stream to the bodyof water. Over time, and with a discrete body of water, hypohalic acidwill have been carried by the pump and dispersed throughout the body ofwater, where it remains active in sanitizing the water. Similarly,microbicidal metal ions are typically introduced by removing a flowstream from a body of water, contacting the flow stream with a sourcefor the microbicidal metal ions, and returning the treated flow streamthrough the body of water. In either case, flow rates and residencetimes for the removed flow streams are selected so that the water is incontact with the electrolytic cell or the source of metal ion for asufficient time to achieve the desired results, i.e., the desiredchlorine or metal ion concentrations. Alternatively, if a flow stream ofwater, rather than a body of water, is to be purified, the entire flowstream of water can be contacted with the electrolytic cell and thesource of metal ions.

In a specific embodiment, it has been found desirable to maintainseparate flow paths for water passing through the electrolytic cell andfor water into which microbicidal metal ions are introduced. This limitsthe likelihood of any undesirable interactions between the metal ionsand the electrolytic cell (such as the plating out of metal ions ontothe electrodes, which may result if water containing high concentrationsof metal ion pass through the electrolytic cell) as well as between thehypohalite acid(s) or hypohalite ions and the source of metal ions.

FIG. 1 is a perspective view of a water sanitization apparatus 100according to certain of the various embodiments of the invention. Inthese embodiments, the water purification apparatus 100 includes ahousing 102. Because chlorine will be generated within the housing bythe electrolytic assembly, the housing is desirably at least primarilyconstructed of chlorine resistant materials. ABS(Acrylonitrile-Butadiene-Styrene) plastic resin is one such suitablematerial, but any appropriate chlorine resistant material can be used.The housing material preferably can be either opaque, or polished so asbecome transparent. The housing 102 includes an optional detachablebottom portion 104 that has apertures for an inlet and an outlet, andpreferably, for a pressure relief valve, each of which are shown in FIG.2. The housing 102 also includes a vessel bottom 106, and a vessel top108. At least a portion of the vessel bottom 106 is transparent toprovide visual verification of the flow of water through the apparatus100. Also, the operator can visually verify that the electrolyticgenerating portion of the device is operating, because a byproduct ofthe chlorine generating reaction is the production of bubbles ofhydrogen gas. By visually inspecting the operation of the apparatus 100,an operator can ensure that water is flowing through the apparatus 100,and that the water is being electrolytically sanitzed, as explainedabove. The components of the housing are held together at least in partby a rear clamp 110 and a front clamp 112. The clamps 110, 112 providestructural integrity and ease of assembly to the housing 102, and arepreferably constructed of a strong, lightweight material such asaluminum.

FIG. 2 is a exploded perspective view of the components of the watersanitization apparatus according to FIG. 1. The vessel top 108 includesports 202, 204 for installing and removing the metal generator 206 andan electrode assembly cartridge 208. The metal generator port 202 ispreferably sealed by a removable metal generator cover 114. The metalgenerator 206 is capped on one end by a metal generator cap 207, whichprotrudes through the opening 115 in the metal generator cover 114, andmay include a flange around its circumference. The electrode assemblycartridge port 208 is preferably sealed by a removable electrodeassembly cartridge cover 116. The electrode assembly cartridge cover 116includes an electrical port 210 through which an electrical connector118 couples the electrode assembly cartridge 208 to a controller 119,via a lead 120. The electrical connector 118 is mechanically locked inplace and sealed from the elements. Both the metal generator cover 114and the electrode assembly cartridge cover 116 may optionally betethered to the housing 102 to decrease the chance of loss while theapparatus 100 is being serviced.

To protect the components of the apparatus 100 from environmentalcontamination, and to prevent leakage of water, the apparatus is sealed.Either or both the metal generator port 202 and the electrode assemblycartridge port 204 includes a preferably threaded port that couples witha cover in a watertight union. The cover desirably includes a mechanicallocking ring, and a jacking ring. For example, the metal generator cover114 is rotated around the threaded end of the metal generator port untilthe mechanical locking ring has been overcome, at which time the metalgenerator cover 114 is engaged at the appropriate tightness, and cannotbe tightened further. The non-rotating “jacking” ring is desirably acomponent of the cover 114, and is interposed between the cover 114 andan o-ring 212. One surface of the jacking ring provides a bearingsurface against which the cover 114 rotates during tightening anduntightening. The opposing surface of the jacking ring applies verticalpressure compressing the o-ring 212, while preventing the rotating cover114 from mechanically stressing the o-ring 212 and from causing themetal generator cap 207 to rotate. The o-ring 212 is interposed betweenthe jacking ring and the base of the threaded end of the metal generatorport 202. Alternatively, the o-ring 212 is interposed between thejacking ring and a flange around the metal generator cap 207.Compressing the o-ring 212 creates a seal that prevents water and othermaterials from escaping or entering the housing 102 through the metalgenerator port 202. The watertight seal is achieved in the same fashionwith respect to the electrode assembly port 204, the o-ring 214, and theelectrode assembly cartridge cover 116.

The vessel top 108 may also utilize a mechanical locking ring, jackingring, and/or a housing o-ring 216 to couple with the vessel bottom 106.Preferably, however, the vessel top 108 and the vessel bottom 106 arenot easily disengaged after being assembled together, in order toprevent tampering or improper repair or reassembly by the user.

The water sanitization apparatus 100 preferably includes a check valve218 and a pressure relief valve 220, the operation of which will bedescribed in more detail below.

FIG. 3 is a cross-sectional view of a water sanitization apparatus 100according to FIG. 1. Water enters the housing 102 via the inlet 300. Atleast a portion of the water entering the inlet 300 is directed throughmedia contained in the metal generator 206. The metal generator 206 is acontainer, desirably cylindrical, that includes at least one vent 302and a media area 304. The bottom (inlet side) of the metal generator 206rests on or near the vessel bottom 106. In certain embodiments of theinvention, some of the water entering the metal generator 206 isexpelled through the vent 302 without passing though the media area 304.The inlet pressure causes the vented water to travel around the metalgenerator 206, and the non-vented water to pass though the media area304. Thus, the metal concentrations in the non-vented water areincreased by contact with the media in the metal generator 206. Afterpassing through the metal generator 206, the treated water is expelledthough slots 306 at the top of the metal generator 206, and blends withthe vented water that has been channeled around the metal generator 206.The pressure of the flowing water opens check valve 308, allowing theblended water to enter the electrolytic chamber and to contact electrodeassembly cartridge 208.

In addition to allowing and controlling water flow between the metalgenerating chamber and the electrolytic purification chamber, the checkvalve 308 also functions as a safety feature to prevent destruction ordamage to the apparatus 100 that would result were the apparatus 100installed backwards, i.e., with the inlet and the outlet reversed. Ifthe apparatus 100 is incorrectly installed, the check valve 308 includesa flapper assembly that will not open, thereby preventing water that hasbeen passed though the electrode assembly cartridge 208 from enteringthe metal generator 206. Thus, the check valve 308 allows the flow ofwater from the metal generator 206 to the electrode assembly cartridge208, and prevents flow of water from the electrode assembly cartridge208 to the metal generator 206. Furthermore, at least a portion of thewater flow will be directed through pressure relief valve 220 andexpelled from the housing in a manner that is visible to the operator,to signal the operator that the device should be reinstalled properly.

The electrode assembly cartridge 208 contains an electrode assembly 310,and is preferably a “full flow cell” in that all of the water enteringthe housing 102 can pass through the electrode assembly 310. FIG. 4 is aperspective view of an electrode assembly 310 according to certain ofthe various embodiments of the invention. The electrode assembly 310includes a series of stacked and nested electrode plates 402, desirablymade of coated titanium, with alternating spacers 404. Each spacer 404is constructed of an insulating material, such as plastic, and desirablyincludes an insulating fin extending away from each of the edges of theplate 402 generally in the plane of the plate. The insulating fins helpto increase electrolytic efficiency by helping to force electrons topass between electrodes, rather than traveling around the electrodes. Aset of leads 406 is electrically connected to the upper portion of thetop and the bottom electrode plates 402. Another lead 408 iselectrically connected to the lower portion of the top and the bottomelectrode plates 402. Alternatively, a single lead may be electricallyconnected across the top electrode plate 402, wrapping around the bottomof the electrode assembly 310, with an additional electrical connectionacross the bottom electrode plate 402.

FIG. 5 is a cross-sectional view of an electrode assembly according toFIG. 4. The spacers 404 are interspersed between the electrode plates402 to create spaces that allow water to flow between the plates. Thespacers 404 separate adjacent electrode plates 402 preferably by adistance of about 10–12 mm. The top and bottom edges of each spacer 404are each no wider than the electrode plate 402. Each side edge of eachspacer can be wider that the electrode plate 402, such that stackingspacers 404 creates a gap between adjacent electrode plates 402. Eachspacer 404 can be beveled at least on the edge positioned at the top endof the electrode assembly, thereby encouraging the flow of water betweenthe electrode plates 402. Water flow between the plates may be laminaror slightly turbulent, provided that the flow is sufficiently rapid thatchlorine produced at the electrode surfaces is rapidly cleared. Highlyturbulent flow is generally avoided, as it is more likely to inducecavitation, which can bring damaging oxygen into contact with thesurfaces of the electrode plates 402.

Electrons desirably pass from one electrode plate 402 to the nextadjacent plate. It is desirable to at least minimize “electron jumping,”i.e., the passage of electrons from one electrode plate 402 to anynonadjacent electrode plate 402. Thus, the spacers desirably form“surrounds” that insulate the sides and edges of the electrodes, eachsurround extending away from the edges of the electrode plate 402 in afin-like configuration. Covering the sides and the edges of eachelectrode 402 can also provide protection from corrosion. In certainembodiments of the invention, the surrounds are prefabricated andsubsequently assembled with the electrode plates 402. In certain otherembodiments of the invention, the edges of each electrode plate 402 areovermolded with an insulating material before the electrode plates 402are assembled into the electrode assembly 310. Thus, the surrounds maybe integral to the spacers, or may be separate components.

The electrode assembly preferably contains a plurality of electrodeplates 402, sufficient for treating the quantities of water to bepurified. Rather than increasing the number of electrode plates 402 totreat different quantities of water, the water treatment capacity of theapparatus 100 can be controlled by varying the surface area of eachelectrode plate 402, preferably without varying the size of theelectrode assembly cartridge 208 or the housing 102. As shown in FIG. 6,the electrode plate size is varied, while the peripheral dimensions ofthe spacers 404 can remain constant. For example, in the embodimentsshown, spacer 602 insulates electrode plate 604. Electrode plate 604 issized to treat the maximum amount of water for which the electrodeassembly cartridge is rated. In contrast, electrode plate 606 is sizedto treat 78% of the maximum rating of the electrode assembly cartridge.Thus, if electrode plate 604 is sized for an electrode assembly with thecapacity to treat a 45,000 gallon pool, then electrode plate 606 issized for an electrode assembly with the capacity to treat a 35,000gallon pool. A “blank” or adapter 610 is used to insulate and stabilizeelectrode plate 606 within spacer 608, which has the same dimensions asspacer 602. Alternatively, electrode plate 612 is insulated andstabilized within spacer 614, which has the same peripheral dimensionsas spacers 602 and 608, but includes additional insulating material tocompensate with the smaller dimensions as compared to electrode plate604.

Using the same number of plates 402 regardless of the volume of water tobe treated has several advantages. In particular, varying only the platesize allows the standardization of various other components in thedevice, thereby decreasing inventory costs incurred from maintaining asupply of various sized transformers and housings 102. In addition,because the material used to make the plates is expensive, using only asmuch material as is necessary for a particular size pool provides costsavings as well.

As mentioned above, a byproduct of the chlorine generating reaction inthe electrode assembly cartridge 208 is the production of hydrogen andother gases, such as oxygen, ozone, and chlorine. If the flow of waterin the apparatus 100 decreases or ceases due to a blockage or pumpfailure, gas produced in the electrode assembly cartridge 208 is notcontinually flushed out of the apparatus 100. To protect against adangerous buildup of hydrogen and/or other gases, or to provide forrelief of excess water pressure from other sources such as pump pressurespikes, the housing 102 advantageously allows safe dissipation of excesspressure via the pressure relief valve 220. The pressure relief valve220 can be mechanical and/or electrical, and desirably operates when aninternal pressure within the apparatus exceeds a preset value (“triggerpressure”). Operation of the pressure relief valve 200 can be triggeredmechanically or electronically, such as by a spring or a pressuresensitive switch. The pressure relief valve 220 is preferably set toactivate, i.e., to open, at the trigger pressure, within an acceptabletolerance (e.g., 50+/−10 psi).

After passing through the electrode assembly 310, the now sanitizedwater exits the housing via the outlet 312.

Various embodiments of the invention include an electronic controller119 that controls the operation of the water sanitization apparatus 100.The controller 119 preferably includes a constant voltage, constantcurrent density power supply that drives a variable output current inthe electrode assembly cartridge 208. However, in other embodiments ofthe invention, the controller 119 may use a constant current, variablevoltage power supply. The controller 119 may include an internalrechargeable battery to keep control circuits energized in the event ofa power failure. The controller 119 can include a cartridge lifeindicator timing circuit that indicates the end of the useful life ofcertain components of the apparatus 100, particularly, the media of themetal generator 206 and the electrode assembly cartridge 208. Thecontroller 119 may also include at least one additional timing circuitto control various functions of the controller. Preferably, thecontroller 119 includes a non-volatile memory that retains previouslyestablished control settings.

The output current of the controller can be visually apparent to anoperator through the implementation of a series of LEDs or otherindicators on the controller. In one embodiment, six LEDs indicate theoutput current setting. For example, during a period in which theapparatus is inoperative, only one LED may be on, thereby indicatingthat the apparatus 100 is receiving power, but that the output currentsetting is zero. As another example, if the output current falls below80% of the output current setting established by the controller, a “lowsalt” condition is indicated. Preferably, an LED or certainconfiguration of LEDs lights to visually communicate the “low salt”condition to the operator.

One of the functions of the controller is to monitor and ensure the safeoperation of the apparatus 100. More specifically, the controllercontinually monitors the flow of water in the apparatus 100. Thecontroller checks for continuity between electrical contacts positionedinside the apparatus 100, preferably inside the electrode assemblycartridge 208. If water is flowing through the apparatus 100, thecontroller will sense continuity. If the water in the apparatus 100 hasbeen displaced, such as by a buildup of hydrogen gas, the controllerwill not sense continuity. The controller disrupts the supply of powerto the electrode assembly cartridge 208 if the controller detects thatthere is a lack of continuity between the electrical contacts.Preferably, a specific LED or a certain configuration of LEDs will lightto visually communicate a “no flow” condition.

In certain embodiments of the invention, the metal generating andelectrolytic portions of the device are disposed above the inlet andoutlet ports, forming an inverted U. The U-shaped (∩) physicalconfiguration of the apparatus 100 has the advantage of forming a “gastrap.” In these embodiments, the apparatus 100 is plumbed atop twovertical pipes, a first pipe being threaded or glued into the inlet 300and a second pipe being threaded or glued into the outlet 312. Waterflows up the first pipe and into the apparatus 100, and treated waterflows out of the apparatus 100 and down the second pipe. If in-lineconfiguration is used, and the water flow decreases or ceases, any gasbuildup may tend to travel along the second pipe and into a downstreamfilter, eventually displacing the much larger volume of water in thefilter (which can be the size of a barrel), and creating an explosionhazard. By contrast, the inverted U configuration prevents thedisplacement of such a large volume of water because excess gas willtend to accumulate at the top of the inverted U, thereby only displacingwater in the apparatus 100. Once the accumulated gas displaces enoughwater to cause a loss of continuity within the apparatus 100, theapparatus 100 will be powered down by operation of the continuity checkperformed by the controller. If the continuity check fails to detect theloss of continuity, the displacement of water in the inverted U can onlyproceed until no water contacts the electrode assembly 310. If no watercontacts the electrode assembly 310, current cannot flow between theelectrodes in the electrode assembly 310. Thus, the electrolytic processceases, and gas can no longer be produced.

During regular operation, deposits of minerals such as calcium carbonateor other insoluble salts can accumulate on the electrode plates 402 as aresult of electrochemical reactions with dissolved salts in the water.The resulting buildup of scale can decrease the efficiency of theelectrode assembly 310 and require its eventual replacement. Preferably,the controller and the electrode plates 402 are designed to enableself-cleaning of the electrode assembly 310 by periodically reversingthe polarity of the potential difference (and thus, the output current)across the electrode assembly 310. The periodic reversal of polarityreduces the frequency with which the electrolytic assembly must becleaned. In fact, without periodic reversal, an operator would likelyneed to remove scale from the electrode plates 402 approximately onceweekly, typically by soaking the plates in an acid. The controller isprogrammed to continually implement a polarity reversal cycle. Forexample, in one embodiment, the reversal cycle consists of 5.8 hoursrunning time, followed by a shutdown (relaxation) period of 5.5 minutes,followed by 5.8 hours running time at reversed polarity. The relaxationperiod is believed to allow the surface of each electrode plate 402 todepolarize. The electrode plates 402 is coated on both sides to make theplate suitable for use as either a cathode or an anode as necessaryduring periodic reversal of polarity. Preferably, a specific LED or acertain configuration of LEDs will light to visually communicate thepolarity condition.

Another function of the controller is its ability to cause the watersanitization apparatus 100 to at least temporarily “super-chlorinate”water, particularly in response to heavy use by bathers, etc. During asuper-chlorinate cycle, the controller raises the nominal output currentin the electrode assembly 310 by approximately 15% for a predefinedperiod of time, at the end of which, the controller lowers the nominaloutput current to routine levels. Preferably, a specific LED or acertain configuration of LEDs will light to visually communicate a“super-chlorinate” condition to the operator.

The controller also includes various switches that enable the activationand deactivation of the various functions of the controller. Inparticular, the controller preferably includes a switch to adjustchlorine output, a switch to activate the super-chlorinate cycle, aswitch to reset cartridge life indicator, a power on/off switch, andvarious switches for testing the controller. The test switches arepreferably hidden from the user, so as to be accessible by professionalinstallers or servicers. In certain embodiments, all indicating LEDs andcontrol switches are fitted to a single printed circuit board assembly.In an example of one LED configuration: LED 1 indicates a “low salt”condition; LED 2 indicates a “no flow” condition; LED 3 indicates a“super-chlorinate” condition; LED 4 indicates that the metal generatormust be replaced soon; LED 5 indicates that the metal generator must bereplaced immediately; LED 6 indicates that the electrode assemblycartridge must be replaced soon; LED 7 indicates that the electrodeassembly cartridge must be replaced immediately; and LEDs 8–13 indicatethe output current setting of the controller.

The controller 119 may have several predetermined output currentsettings that define the possible output currents in the electrodeassembly 310. In each embodiment, the controller 119 seeks to maintain agiven current density on each plate 402 to compensate for conductivityswings due to variations in the level of salinity. Without thiscompensation, an oversalinated pool would cause overcurrent conditionswithin the apparatus 100, potentially burning out components of theelectrode assembly cartridge. In one embodiment, there are four possibleoutput current levels that can be selected by fitting an internal shuntin the controller 119. The current and voltage levels can vary accordingto the particular application. In this example, the four possible outputcurrents C1 through C4 are generated at a constant voltage of preferably22 volts (DC), and can be expressed as follows:

-   -   C1=1.5 amps DC (super-chlorinate 1.725 amps DC);    -   C2=2.5 amps DC (super-chlorinate 2.875 amps DC);    -   C3=3.5 amps DC (super-chlorinate 4.025 amps DC); and    -   C4=4.5 amps DC (super-chlorinate 5.175 amps DC).        The various current settings are preferably preset, and are        retrieved from the memory of the controller 119 to enable the        operator to select from two or more allowable current settings.

Certain embodiments of the invention possess additional features. Thehousing can be designed to be completely watertight, preferablywithstanding pressures of 100 psi or higher, and more particularly, 2bars (29 psi). However, elements of the metal generator and theelectrode assembly are easily accessed and replaced by a user or otheroperator. An optical reminder system alerts the operator to the need toreplace elements, preferably before the effectiveness of the elementshas been exhausted. Visual and/or electronic indicators can beimplemented to relay the status of the apparatus to an operator.

An advantage of the various embodiments of the water sanitationapparatus 100 is its ease of installation and maintenance. The housing102 is compact, allowing for installation in space restricted areas. Theinstaller couples the apparatus 100 with the source of the water to betreated by connecting a suitable water carrying conduit, such as a 2″PVC (polyvinyl chloride) pipe, to the inlet 300. The inlet conduit isfurther connected to the source of the water to be sanitized. Theinstaller then connects a second conduit to the outlet 312, for allowingegress of sanitized water.

The operator can also easily install or replace metal generator 206 orelectrode assembly cartridge 208. To do so, the operator simply loosensthe appropriate metal generator cover 114 or electrode assembly cover116 and disengages the corresponding cartridge. A new cartridge isengaged, and the cover is retightened. As mentioned above, thecontroller LEDs alert the operator to the need to replace cartridges. Inone embodiment, replacement of the metal generator 206 is indicatedevery six months, and replacement of the electrode assembly cartridge isindicated every three years.

Certain embodiments of the water sanitation apparatus 100 utilize visualcoding to assist in ensuring that the proper interchangeable componentsare utilized for a given application. For instance, the color and/orshape of the metal generator cover 114 and/or the metal generator cap207 may indicate the capacity of the metal generator 206. The colorand/or shape of the electrode assembly cartridge cover 116 may similarlyindicate the size of the electrode plates 402 within. The color of thehousing 102 may indicate the maximum volume of water that can be treatedby any combination of components with the apparatus 100.

FIG. 7 is a side view of an alternative embodiment of a watersanitization apparatus 100. In this embodiment, the metal generator 206and the electrode assembly cartridge 208 are disposed in series alongthe length of the housing 700. The metal generator 206 and the electrodeassembly cartridge 208 are separated by a check valve which preventsbackflow from the electrode assembly cartridge to the metal generator206. Water enters the inlet 702 and exits through the outlet 704. Themetal generator (not shown) can be accessed via a metal generator cover(not shown) that fits on the threaded end 706 of the housing 700. Theelectrode assembly cartridge 208 can be accessed via an electrodeassembly cartridge cover (not shown) that fits on the threaded end 708of the housing 700. The housing is preferably transparent to enablevisual inspection of the operation of the apparatus 100. This embodimentpreferably also includes safety features such as a pressure reliefvalve, and a continuity sensor.

The foregoing description of various aspects, features, and embodimentsof the invention has been presented only for the purpose of illustrationand description and is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Many modifications andvariations are possible in light of the above teaching. For example, itshould be understood that although the present invention has beendescribed primarily with water flowing through the metal generator andthen through the electrolytic chamber, the principles of the inventioncan be implemented conversely. The materials used for each element ofthe water sanitization apparatus are limited only by the mechanical,electrical, and chemical properties of the materials. Several shapes,sizes and configurations are disclosed, although many other shapes,sizes, and configurations are possible without departing from the scopeand spirit of the invention.

1. An apparatus for purifying water, comprising: an inlet, for receivingthe water; a metal generating chamber in fluid communication with toinlet, the metal generating chamber comprising media that introducesmetal into the water; an electrolytic purification chamber in fluidcommunication with the metal generating chamber, comprising an electrodeassembly cartridge having at least two electrodes; and an outlet influid communication with the electrolytic purification chamber.
 2. Theapparatus of claim 1, further comprising a housing that encloses themetal generating chamber and the electrolytic purification chamber, andconfigured to: direct at least a portion of the water through the metalgenerating chamber; direct the water through the electrolytic chamber;and direct the water out of the housing via the outlet.
 3. The apparatusof claim 2, further comprising a pressure relief valve in fluidcommunication with the interior of the housing.
 4. The apparatus ofclaim 2, wherein the housing is formed from a chlorine-resistantmaterial.
 5. The apparatus of claim 2, wherein the housing is at leastpartially transparent.
 6. The apparatus of claim 5, wherein thetransparent portion of the housing allows visual confirmation of waterflow and operation of the electrode assembly cartridge.
 7. The apparatusof claim 1, further comprising a check valve disposed between the metalgenerating chanter and the electrolytic purification chamber, andadapted to allow flow of water from the metal generating chamber to theelectrolytic purification chamber, but to prevent flow of water from theelectrolytic purification chamber to the metal generating chamber. 8.The apparatus of claim 1, wherein the electrode assembly cartridgecomprises a plurality of metal plates which function as electrodes, andwherein each pair of plates is associated with an insulating spaceradapted to maintain an appropriate gap between the pair of plates. 9.The apparatus of claim 1, wherein the electrode assembly cartridgefurther comprises at least one insulating surround disposed around theedge of each metal plate, thereby reducing contact between the metalplate edges and water.
 10. The apparatus of claim 9, wherein at leastone surround further comprises an insulating fin extending from thesurround in one or more directions.
 11. The apparatus of claim 1,wherein the metal generating chamber and the electrolytic purificationchamber are vertically oriented and disposed above the inlet and outlet,respectively.
 12. The apparatus of claim 1, further comprising acontroller that is coupled to the electrode assembly cartridge and thatcontrols the operation of the apparatus.
 13. The apparatus of claim 12,wherein the controller comprises a power supply electrically connectedto the electrode assembly cartridge, and capable of inducing a currentto flow across the electrodes.
 14. The apparatus of claim 13, whereinthe controller is adapted to reverse the polarity of the potentialdifference across the electrode assembly.
 15. The apparatus of claim 14,wherein the controller comprises control electronics adapted to causethe power supply to reverse polarity periodically and automatically. 16.The apparatus of claim 13, wherein the controller comprises controlelectronics adapted to maintain a substantially constant current densityto the electrode assembly cartridge.
 17. The apparatus of claim 13,wherein the controller comprises control electronics adapted totemporarily increase current density to the electrode assemblycartridge.
 18. The apparatus of claim 13, wherein the controllercomprises control electronics and memory circuits adapted to storeinformation about the most recent settings of the control electronics.19. The apparatus of claim 18, wherein the control electronics furthercomprise circuits adapted to retrieve information from the memorycircuits and change the current settings to the retrieved settings. 20.The apparatus of claim 12, wherein the electrode assembly cartridgecomprises a continuity sensor disposed within the housing, and adaptedto allow the controller to sense when the volume of the water in thehousing drops below a preset level.
 21. The apparatus of claim 20,wherein the continuity sensor is electrically connected to a shut-offcircuit adapted to discontinue power to the electrode assembly cartridgewhen the water volume in the housing drops below the preset level. 22.An apparatus for purifying water, comprising: a housing having an inletand an outlet for water to enter and leave; a metal generating chamberwithin the housing, in fluid communication with the inlet or outlet andcomprising media for introducing metal into the water; an electrolyticpurification chamber in fluid communication with the inlet or outlet,and in fluid communication with the metal generating chamber, comprisinga plurality of electrodes capable of generating halogen from dissolvedhalide ion; wherein when the metal generating chamber is in fluidcommunication with the inlet, the electrolytic purification chamber influid communication with the outlet, and conversely.